Feature request: Intermediate Progress Style

[ThatTonybo]

• Summary
  An intermediate style for the Progress element

• Can you provide a basic example?
  Here is a Codepen example I found, that shows it well. Most libraries and systems have this kind of style, however.

• Motivation
  Useful as an alternative to the loading spinner, or for keeping to design if the min/max/current values aren't yet known. In my own case, the progress bar is shown before the maximum value is shown, and having an intermediate style until then would be very useful.